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Company Says FCC Should Consider Using SAS in 4.9 GHz Band

May 19, 2016–The FCC should consider employing a spectrum access system (SAS) to maximize use of the underutilized 4.9 gigahertz band, Federated Wireless, Inc., said in an ex parte filing today in WP docket 07-100, PS docket 06-229, and WT docket 06-150. “In the Citizens Broadband Radio Service (‘CBRS’), the Commission adopted an innovative three-tier regulatory framework, administered by a SAS, to enable spectrum sharing among different classes of users while providing interference protection to incumbents in the 3550-3700 MHz band,” Federated noted in its filing.

“Federated Wireless notes that, as is the case in the CBRS [Citizens Broadband Radio Service], the 4.9 GHz band currently supports operations by disparate users, including radio astronomy, naval training operations, public safety and critical infrastructure operations,” the filing added. “However, the 4.9 GHz band is also underutilized in significant portions of the country and, as such, is a prime candidate for sharing spectrum among between incumbent and newly authorized commercial or private operations.”

Federated said that its “attached presentation provides a hypothetical regulatory framework for the 4.9 GHz band, conceptually very similar to the CBRS structure, leveraging SAS technology to enable spectrum sharing. In such a framework, radio astronomy would receive the highest levels of protection, akin to the protection afforded to incumbent FSS operations in the CBRS. Public safety and critical infrastructure users would be licensed in the second tier, providing them guaranteed spectrum access and replacing today’s inefficient manual coordination processes with frequency coordination and interference management through the SAS, in real time.

“In the third tier, commercial or private operators could utilize the 4.9 GHz band to provide wireless broadband services,” the filing added. “The Wireless Innovation Forum (‘WINNF’)—a cross-industry stakeholder group made up of wireless operators, equipment manufacturers, incumbent satellite users, and SAS operators—has developed, in close consultation with the Commission and observers including the Department of Defense and the National Telecommunications and Information Administration (‘NTIA’), CBRS industry standards. These standards specify processes that are useful for a potential sharing regime in the 4.9 GHz band, including: communications between a SAS and radios; communications among different SASs; and, of particular importance in the 4.9 GHz context, ensuring the security of the shared use ecosystem.

“Federated Wireless encourages the Commission to take note of the significant standards work that has been done for the CBRS and find ways to utilize those learnings to support sharing in the 4.9 GHz band which will enhance utilization of this valuable spectrum,” the company added. “Although there are many similarities between the CBRS and the 4.9 GHz band, Federated Wireless also urges the Commission to consider the differences between the bands that may impact the business case for prospective SAS administrators and commercial or private operators at 4.9 GHz. For instance, whereas the CBRS encompasses 150 MHz of spectrum, the 4.9 GHz band is only 50 MHz wide, which may raise bandwidth and band plan concerns for prospective operators. The use of overlapping channels in a Wi-Fi-like band plan could mitigate such concerns. In addition, 3GPP Bands 42 and 43, which include the CBRS spectrum, are internationally harmonized, leading to widespread equipment availability and scale-induced cost efficiencies. The 4.9 GHz band, however, is not internationally harmonized, and thus does not offer similar scale efficiencies on equipment. The broad use of 802.11y technology among 4.9 GHz users may mitigate this concern as well.”

Federated also noted that “to operate in the 4.9 GHz band, a SAS administrator would have to collect subscription fees for its services from users in public safety, critical infrastructure and the general access tier. Such services to public safety users can include detecting the presence of naval training operations and coordinating temporary spectrum repacking, similar to how the SAS works with the Environmental Sensing Capability (‘ESC’) in the CBRS, and deconflicting overlapping interjurisdictional spectrum uses, similar to how the SAS manages inter-PAL [priority access licensee] interference in the CBRS. Although public safety and critical infrastructure users may raise concerns about paying such fees, the efficiencies these users will gain from automation of existing, inefficient manual process for frequency coordination will likely more than outweigh any such costs. In addition, as use of the band increases, these efficiencies will increase and further offset the cost of subscribing to a SAS’s services.” – Paul Kirby, paul.kirby@wolterskluwer.com